Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description aligns with the readOnly and non-destructive annotations and adds transparency about subscription-gated behavior and anonymous-call outcomes. It does not fully spell out that no data is modified, but the annotations already cover that and the description adds meaningful access-related behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is concise and information-dense, with no redundant phrases or filler. Three sentences cover purpose, access requirements, and failure mode without unnecessary elaboration.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given that an output schema exists, the description does not need to detail return formats. It adequately covers the tool's data-access context, authentication requirement, and anonymous behavior, making it sufficiently complete for a subscriber-gated read-only data tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema descriptions already cover all six parameters with 100% coverage, so the baseline applies. The description adds some context around derived forward segments and official government-nominal curves, but it does not materially deepen parameter understanding beyond the existing schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: returning official government-nominal curve nodes, slopes, or derived forward segments for one currency. It identifies the specific resource, the action, and the scope in a way that is immediately understandable.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides actionable access guidance: it is a subscriber data tool, requires an FXMacroData API key, and notes that anonymous calls return subscription_required with a subscribe link. It stops short of comparing this tool to sibling alternatives, but the access guidance is clear and useful.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.